Airfoil



Junew, 1931. H H SEMMS' 41,809,913

AIRFOIL original Filed Nov. 19, 1929 gwuentoi Patented June 16, 1931 UNITED STATES PATENT OFFICE:A

ARRY H. SEMMES, OF CHEVY CHASE, MARYLAND, ASSIGNDR T BENDIX AVIATION CGRPORATION 0F NEW YORK, N. Y., A. CORPORATION 0F DELAWARE y Original applicationiled November 19, 1929, Serial No. 408,375. Divided April; 12, 1930. Serial No.443,782. C

-Th'e invention relates to airplanes and l more particularly has reference to an airfoil construction therefor which strength and rigidity. v

This application is a division ofan application Serial Number' 408,37 5, filed November19,1929. f

At present airfoils or airplane wings are constructed so as'to support a load of from 12 to 16 times the weight of the airplaneitself. Beyond these limits structural weight possesses great is added to such an extent that theairplane isV impractical and strength must be sacrificed v for weight. A

It is well known dynamic loads are created by the actuation of the airplane control surfaces and at times these loads may well ex! ceed the structural strength of the wings andV cause them to fail. The amount of these dyr l Anamic loads are greatly influenced by the time factor within which the control surfaces of an airplane areoperated. By arranging the control surfaces so that they may not be actuated quickly excessive stra'ins upon the wings may be prevented. While this has been successfully accomplished, it is evident that the easeand the speed with which an airplane may be maneuvered into various positions is considerably lowered.

It is' customary in the present practice to construct an airfoil of a plurality of spars and ribs, the formerbeing positioned at denite and equal distances along the transverse axis or'cord of the airfoil, while the latter are positioned at equal distances apart from each other along the longitudinal axis of the airfoil. While such structure has successfully furnished a strength sufficient to support a load, within the limits mentioned above, it may be observed that no attempts have been made to employ a considerable number of sparsand ribs possessing relat1vely small cross sect1ons and pos1t1oned 1n groups at the-points or within the zones where the resultant of the load carried by the wing takes e'ect so as to increase the structural strength while at the same time reducing the weight of the airfoil.

\ It is also quite customary to form the spars and ribs, employed in'an airfoil construction,

Amrorr.

and this application filed of a plurality of -members usually a beam or girder-like member having a web, and one or more flanges. Generally these members are formed separately and are secured to the web. It is apparent that such construction possesses the inherent defect of requiring an unnecessary multiplicity of parts.

The major object of the invention is the design of an airfoil of light weight which posframe, the longitudinal and transverse members of which are grouped in close proximity `to each other at the points or within the zone of the resultant load carried by the airfoil.

Yet another object of the invention is the design of an airfoil having an integral structure which is of fan-like shape.

A further object of the invention is the devising of an airfoil construction employ.- ing aa'plurality of spars arranged in a fanlike shape which are employed in conjunction with ribs arranged at varying distances apart from each other.

y Still a further object of the invention is the devising of an airfoil construction comprising an integral frame which may be em# ployed with an airfoil having a'longitudinal outline tapered as to thickness, or a tapered dpermitting ease of fabrication and of` inexpensive construction.

With these and other objects in view, which may be incident to my improvements, the invention consists in the parts and combinations -to be hereinafter set forth .and'claimed, with the understanding that the several necessary elements comprising my invention ma be varied in construction, proportions an arrangement without departing from the spirit and scope ofthe appended claims.

The present invention .deals with airplanes and consists inthe construction of an airfoil therefor which is an integral structure. One method of practically eecting the concept of this invention'is to provide a pluralit of spars positioned at varying distances rom each other along the transverse axis of the airfoil and a plurality of ribs positioned. at varying distances from each other alongthe longitudinal axis of the airfoil. The invention also comprehends the grouping of these members at the points and within the zone of the resultant of the force or load acting upon the airfoil In order to make my invention more clearly understood, I have shown in the accompanying drawings, means for carrying the same into practical eiect without limiting the improvements in their useful applications to the particular constructions, which forthe' purpose of explanation, subJect of illustration.

In the drawings: y Figure 1 is a plan view of an airfoil, with a partvof the wing ,surfacing material rcmoved, constructed in accordance with my invention.

Figure 2 is a cross sectional elevation of have been made the the airfoil shown in Figure 1 and is taken having an aileron 7 an along the line 2 2. l

Figure 3 represents a cross sectional elevation taken along the line 31-3 of Figure 1. Figure 4 is a view similar to Figure 2 but showing an airfoilhaving a longitudinal outline tapered as to thickness.

Figure 5 is .a pictorial representation showing the manner of securing the ribs to the spars. Disclosed in Figure airplane wing generall 11 of the semi-span are a plurality of spars 12. It should be noted that the spars v12` extend outwardly from the base or root por-- tion 11 and are of unequal'length. `More over, the spars are so arranged as to form a substantially fan-like structure. The outer ends of the spars are secured to the leadin and 'trailing edges, the tip, and the ribs o the airfoil, while the inner ends 'of the spars are secured'to the root portion 11 of the fan.

Spars 12 are so arranged that their inner l ends, which are connected to the base portion 11, are at varying distances from each other. l- This construction allows the spars to be ouped in` close proximity to each other wit the zone of center of pressure travel during' flight. f

cross section.' 'Extending from the nner end base, or root as indicated at 12a. Likewise such construction permits the trailing edge, weakened by the cutout portion for the aileron, to be suitably supported and strengthened lby the spars asv shown at 12b.

The ribs 13 arespaced along the longitudinal axis of the airfoil so that their distances from each other vary. Such an arrangement allows the ribs 13a, adjacent to the path ot' the lateral center pressure travel to be grouped in close proximity to each other thus adding strengtheninglqualitics to the airfoil along the lateral position of the resultant lift load. Moreover, a grouping of the ribs may be employed close to the root portion ll as shown by the ribs 13b. By this structural expedient the semi-span may be adequately supported from the fuselage of an airplane.

While only a semiwing span has been shown in thedrawings, it will be well understood that such construction may be equally n well employed with airplanes having a contlnuous wing or wings which passes either over o'r under the fuselage. In such an event a fan structure similar to that shown in Figure l could be placed upon the other or left side of the wing, and would have a common origin with the fan section shown. To accomplish this the `spars forming the fanlike structure on the left side of the span could be connected tothe base portion 11 or a second base portion could be provided if desired.

The construction shown in Figure 1 is disclosed in connection with a wing having an untapered outline and plan-form and also in connection with a wing having a longitudinal outline tapered as to thickness. It is obvious,

however,that the construction just describedk is equally applicable to an airfoil having a long1tud1nal outline tapered as to thickness and a tapered plan-form.

The wing .disclosed in the drawings has its spars and ribs formed of metallic maj terial having a relatively thin transverse material may be employed with the airfoil. The ribs 13 are formed of a plurality of sections and are welded or otherwise' secured between the spars in a manner similar to that described in theV parent application above mentioned. Likewise it may be appreciated that this form of the invention may be equally well constructed of wood. 1 In either instance .fabric wing surfacing material may be emploved if desired. A

It is apparentthat in the fan-like structure by providing a considerable-number of spars and ribs having a thin cross. section the advantages of a comparatively light airfoil is obtained. Moreover it is evident that the vfan-like construction valso provides an' integral frame, any member of which upon being stressed will transmit a portion of its Also sheet metal surfacingA load to the other members of the airfoil. Likewise the advantages derived from grouping the spars and the ribs Within the zone of travel of the 'center pressure of the Wing- Will be appreciated inasmuch as the parts of the Wing atxwhich the resultant stress occurs will be strongly reinforced.

While I have shown Sand described a Wing having av square tip, it is to bev understood that other designs of Wing tips, such for example, as a tip having a negative rake and a tip having a positive rake Will fall Within the scope of the invention. Likewise it is to be understood that the invention comprehends the use of an airfoil section, as for example a section having a iat bottom cord, a double cambered section, a section having its under surface entirely concave, a combinationof a concave and a convex section or any combination of these. .j

It `is desirable to have means accessible to the interior of an airfoil so that the ribs and spars may be frequently inspected. In

the event that sheet metal surfacing material is employed andthis feature is desired'in connection with the Wing it isobvious that a ppxrtion of the upper surfacing material of t e airfoil maybe formed of sheet metal l and the remainder of fabric.

The features of the airfoil construction will 1 -be appreciated fromthe foregoing description. It may be vseen that an airfoil having an integral supporting frame forme/d of a comparatively great number of spars and ribs of thin cross sectionI has been designed.

l Moreover, by grouping the spars and ribs at points Within the zone Where the greatest load upon an airfoil occurs, an exceptional strong or rigid construction has been provided. Likewise it is apparent that all the membersv of the airfoil resist loads or stress upon any y Vparticular member and all of the members act as bracing members for each other.I

Finally it may be seen that an airfoil of v simple construction, comparatively small Weight, and inexpensive fabrication has been devised.

While I have shown and described the prel ferred embodiment of my invention, I vvish it to be understood that I do not confine my self to the precise ldetails of construction herein set forth, by Way of illustration, as it is apparent that many changes and variations 'l may be made therein, by those skilled in the art, Without departing from the spirit of the invention, or exceeding the scope of the apenV ing distances from each other, the spars Within the zone of center of pressure travel of the `spars adjacent the root Wing and the spars near the trailing edge ofk the Wing being grouped in close proximlty to each other. l

3. An airfoil construction comprising a plurality of spars arranged in a fan-like shape, the root of said fan being adjacent to a. fuselage of an airplane, the ends of said spars adjacent the root portion of the fan being positioned at varying distances from each other,

and a plurality of ribs connected to said spars,

the ribs being positioned along the longitudinal axis of the airfoil .atl varying distances from each other.

4. An airfoil construction comprising a plurality of spars arranged in a fan-like shape, the root of said fan being adjacent to a fuselage of an airplane, the ends of said being positioned at varying distances from eachl other, and a plurality of r ib s connected to the spars, the ribs being posltloned along the longitudinal axis of the airfoil at varyingv distances from each other, those ribs Within the zone of lateral center of pressure travel of the airfoil being grouped in close proximityto each other.'

5. An airfoil construction comprising a plurality of spars arranged in a fan-like shape,` the root of said fan being adjacent to a fuselage of an airplane, the ends of said spars adjacent the root portion of the fan being positioned at varying distances from each j other, the spars within, the zone of center of pressure travel along the chord ofthe airfoil and the spars near the trailing edge of the Wing being grouped in close proximity to each other, and a plurality of ribs connected to said spars, said ribs being positioned along the longitudinal axis of the airfoil at varying distances from .each

other.

6. An airfoil construction comprising a ortion of the fan icc plurality of spars arranged in a fan-like shape, the root of said fan being adjacent to a fuselage of an airplane, the ends of said spars adjacent the root portion of thefan being positioned Aat varying distances from each other, the spars within-the zone of center of pressure travel along the chord ofthe alrfoil and thespar's near the trailing edge of the Wing being grouped in close proximity to each other, and a plurality of ribs connected to said spars, said ribs being positioned\along the longitudinal axis of the airfoil at `varying distances from eachv other, those ribs within the zone of lateral center of f pressure travel of the airfoil being grouped in close proximity to each other.

7. An airplane Wing construction having a plurality of spars, said spars positioned so 5 as to form a substantially fan-like structure within each semi-span of the wing, `said spars originating from a rib member forming a root for the fan and positioned perpendicular to the longitudinal axis of the wing, the ends of said spars adjacent the root being at varying distances from each other,- all of said spars extending outwardly towards a wing tip, some of said spars being secured to the leading edge of the Wing, other of said spars being secured to the trailing edge of the wing, and still other 'of said spars being secured to the tip of the wing.

8. An airplane wing construction compris ing a plurality of one-piece continuous spars l arranged in a fan-like shape, the root of said fan being adjacent a fuselage, of an airplane, the ends of said spars adjacent the root portion of the fan being positioned at varying distances from each other, and a plurality of .25 ribs for the wing, each of said ribs being formed of a plurality of sections of material adapted to be secured between two `adjacent spars so as to be formed in a continuous line across the wing, said ribs being positioned along the longitudinal axis of the-wing at varying distances from each other.

9. An airfoil construction 'comprising a plurality of spars arran ed in a fan-like shape, the root of said gan being adjacent to a` fuselage of an airplane, the ends of said spars adjacent the root portion of the fan being positioned.l at varying distances from each other, with those spars Within the zone of center of pressure travel and with 40 those spars near the trailing edge of the airfoil being grouped in close proximity to each other, and a plurality of ribs connected to said spars, the ribs being positioned along the longitudinal axis of the air-foil at varying distances from each other.

In testimony whereof I aix my signature.

HARRY H. SEMMES. 

